|'Betty's Frank Spencer'|
(even now Betty has the ability to arrest my complete attention)
Noun. Plural pronounced same. Early 19th century.
[French = stupidity, from bête foolish from Old French beste beast.]
A foolish, ill-timed remark or action; a piece of folly.
Part of the problem with beautiful French words like bêtise is not only remembering them in the first place but also remembering how they're pronounced (especially tricky if, like me, you're not a French speaker). However, I do believe I've discovered a rather easy mnemonic for bêtise, French for stupidity, and adopted into English to mean a foolish or ill-timed remark or action.
Frank Spencer from Some Mothers Do 'Ave 'Em is a classic character from British 1970s television, together with his long-suffering (and ridiculously beautiful) wife Betty. Although the programme was largly based around slapstick humour (the hugely talented Michael Crawford renowned for his own stuntwork), Frank's half-wittery was also expressed through his inept and foolish speech, especially when trying to find a job. When it inevitably ends in disaster, one of Frank's catchphrases is 'Ooooh Betty!', a catchphrase that is still commonly echoed across Britain today, especially by those who aren't particularly good at doing impersonations but like to give it a try anyway.
So, to remember bêtise and its pronunciation, just think of 'Betty's Frank Spencer'. If you say that phrase in a French accent, you'll never have any problem remembering either the word or its pronunciation again (granted, this only works if you're British or are familiar with 1970s British television - if you're not, then I'm afraid you'll just have to learn it, and you really should, because it's a smashingly lovely word indeed).